Re: Trivial kernel change

Tigran Aivazian (tigran@aivazian.demon.co.uk)
Mon, 4 Jan 1999 09:41:10 +0000 (GMT)

If some kind soul adds this to the kernel another soul may use it to fill
up your syslog by forking a coredumping program in a loop.

Regards,
Tigran A. Aivazian, http://www.aivazian.demon.co.uk/

On Thu, 31 Dec 1998, Jeffrey Streifling wrote:

> I wonder if some kind soul could add a call to show_regs()
> when a core dump fails so that there is a good way to figure
> out what is causing a userland program to bomb when it
> can't leave a core dump. There seems to be at least two
> possible places to insert this:
> (1) In fs/binfmt_elf.c (and friends if a.out is wanted).
> -Advantage: modification one place for all archBs
> -Disadvantage: less generality of elf_core_dump()
>
> --- binfmt_elf.c Tue Oct 27 10:23:40 1998
> +++ binfmt_elf.c.new Thu Dec 31 20:44:37 1998
> @@ -1067,8 +1067,10 @@
>
> if (!current->dumpable ||
> limit < ELF_EXEC_PAGESIZE ||
> - atomic_read(&current->mm->count) != 1)
> + atomic_read(&current->mm->count) != 1) {
> + show_regs(regs);
> return 0;
> + }
> current->dumpable = 0;
>
> #ifndef CONFIG_BINFMT_ELF
>
> (2) In arch/i386/kernel/signal.c (and other archs)
> -Advantage: customizable, catches any 0-return
> -Disadvantage: must be maintained for each arch
>
> --- signal.c Tue Dec 1 11:28:24 1998
> +++ signal.c.new Thu Dec 31 20:59:45 1998
> @@ -692,6 +692,8 @@
> && current->binfmt->core_dump
> && current->binfmt->core_dump(signr,
> regs))
> exit_code |= 0x80;
> + else
> + show_regs(regs);
> unlock_kernel();
> /* FALLTHRU */
>
>
> Any opinions about which might be better? I'll follow up
> with a more complete patch (all archs, cases, formats, as
> the case may be) if needed.
>
> I know it's pretty late for 2.2.0, but it seems a bit
> trivial for 2.3. Maybe 2.2.1?
>
> Jeffrey Streifling
> <streje@wwc.edu>
>
>
>
> -
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